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I am designing an H-bridge with Arduino to control a small 12V motor. I made a custom PCB with the following schematic however I have a problem with the 2N2222 transistor.

I am using them as a switch two turn on 2 PNP Mosfets. I control this using two Arduino Pins (2 & 3). Each pin turns on an NPN Mosfet and a 2N2222 transistor that turns on a PNP Mosfet in order to obtain a positive and negative output for the motor. When these pins are LOW (OFF), both 2N222 are off and so are all 4 Mosfets.

However, when only one pin is HIGH (ON) both 2N222 are now closed and therefore both PNP Mosfet are triggered. The other NPN Mosfet that is connected directly to Arduino works fine. I cannot understand the issue since the 2N2222 transistor base pin that should remain off has a voltage of 0V which is correct, but the resistance between the emitter and collector pins is close to 0.

The other 2N2222 has a voltage on the base pin of 0.7V and the emitter and collector pins have 0 resistance. This is the same if I try to flip to turn ON the other one and turn OFF the current one that is ON. On the left part of the schematic I just have other connections for reading sensors.

I am not good at all at electronics and I am currently learning, does anyone know what can be the issue?

enter image description here

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    \$\begingroup\$ Well, if your circuit actually looked like a H-bridge, it might be easier to analyse. The whole point of calling a H-bridge by that name is because it forms a letter "H". Think about it. \$\endgroup\$
    – Andy aka
    Nov 5, 2021 at 12:33
  • \$\begingroup\$ @Andyaka Yes, I know however the left part of the circuit is isolated to the one on the right which is a simple H-Bridge \$\endgroup\$
    – Enzo
    Nov 5, 2021 at 12:35
  • \$\begingroup\$ My guess is that your PCB isn’t exactly the same as your schematic. \$\endgroup\$
    – HandyHowie
    Nov 5, 2021 at 13:01
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    \$\begingroup\$ As Andy has said, you will get a lot more interest in this if you draw the schematic so that it looks like an H-bridge. For example, why are 2 of your mosfets drawn upside down, with the ground to the top and the 12v to the bottom? \$\endgroup\$
    – HandyHowie
    Nov 5, 2021 at 13:04
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    \$\begingroup\$ "PNP Mosfets" NPN and PNPs are BJTs, not MOSFETs. \$\endgroup\$
    – winny
    Nov 5, 2021 at 15:54

2 Answers 2

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Thanks to everyone I was able to find the solution of my problem it was the pull down resistor in to 12 V.

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  • \$\begingroup\$ What pull down resistor ? \$\endgroup\$
    – Marla
    Nov 5, 2021 at 15:21
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This works ... Drawing as this ... More clear ? enter image description here

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